BofA: S&P 500 Historically Declines 0.02% in August-October, Averages 7.35% Drop in Down Years

According to Bank of America's recent report released on July 27, the U.S. stock market enters its historically weaker August-October period. Since 1928, the S&P 500 has averaged a 0.02% decline during these three months, with steeper losses—averaging 7.35%—occurring in years when stocks fell overall.

BofA strategists noted that while this seasonal weakness typically prompts defensive positioning among investors, strong rebounds have commonly followed. From October through December, the S&P 500 has historically risen with approximately 74% probability. The bank suggested that seasonal declines could present buying opportunities if supported by technical indicators, allowing investors to reduce risk and build hedges during the weaker summer-autumn period before the stronger November-January stretch.